GB191300745A - Improvements in Starting and Regulating Devices for Electric Motors. - Google Patents

Abstract

745. Olmsted, A. H., and Boothman, L. Jan. 9. Automatic circuit - breakers; interlocked switches.-Relates to a multiple-switch motor starter, in which the separate switches are of the loose handle ' circuit-breaker type and are operated to close in sequence and are released in the reverse order by an overload or underload magnet. The switches 2, 3, 4, 5 are carried by switch arms 15 pivoted at 16 and are operated by separate levers 29 having handles. The levers are connected to the switch arms by toggles comprising links 22, 25 pivoted one to the switch and the other to a fixed lug and connected to links 27 ending in a roller 28, which rests on the operating-levers. Hooks 31 having lateral extensions are pivoted to each switch arm, and when the switch is closed, the extension engages the toggle roller 28 of the next switch, to prevent the roller from sliding along the operating-lever, so that, when the next lever is operated, the toggle closes the switch. The hooks are normally out of engagement with the rollers, and are thrown into engagement by cams 34 carried on a shaft 9 operated by a handle 12; the shaft 9 also carries the armature 8 of an underload magnet 7. Provision may be made for opening the circuit of the magnet 7 on overload. In operation, the handle 12 is raised and the first switch 2 is closed, whereupon current flows through the magnet 7, which holds the shaft 9 and cams 34 in engagement with the catches. The first switch is held closed by a hook 36, Fig. 1, pivoted on a fixed point. The handle 12 is next released, and the switches 3, 4, 5 are closed in succession, each switch being held closed by the hook on the preceding switch when closed; finally, the last switch 5 is held by a mechanical latch 41, Fig. 1. In order to retain the levers closed, a projection 39 on each switch arm engages, when closed, under a projection 40 on the lever of the preceding switch so enabling the operator to release the handle of the preceding switch, and in order to prevent the switches from opening simultaneously, a lug 42 on each switch is adapted to overlap a lug 43 in the preceding switch when closed. On an underload or overload, the switches and levers are opened in the reverse order, except the lever of the switch 5, which is only released by withdrawing the catch 41. The lever of each switch may be provided with a catch, so that the device may be used for regulating as well as for starting a motor.